DE3034252A1 - DEVICE FOR FIELD-ORIENTED OPERATION OF A CONVERTER-DRIVEN ASYNCHRONOUS MACHINE - Google Patents

Abstract

Disclosed is an apparatus for operating a converted-fed asynchronous electric motor which comprises a flux computer for determining the position of the flux vector from the input values for the stator voltage provided by said motor by solving all the electrical quantities of the Park equations describing said motor in a given position of the rotor axis, taking into account the parameter values corresponding to the rotor resistance and the stator resistance of said motor whereby signals corresponding to the position of the flux vector and belonging to a solution, can be tapped from said flux computer; a converter control unit coupled to said flux computer and said convertor rectifier respectively, forming the control quantities for driving the converter rectifier from the determined position of the flux vector and from the nominal input values which fix the components of the stator current vector parallel and perpendicular to the flux vector.

Description

SIEMENS AKTIENGESELLSCHAFT Our symbol Berlin and Munich VPA 80 P 316 7 DE

Device for field-oriented operation of a converter- fed asynchronous machine

The invention relates to a device for operating a converter-fed asynchronous machine with a flow computer and a converter control. The flux calculator determines from the values entered for the stator voltage vector the position of the flux vector describing the magnetic field in the asynchronous machine. The converter control forms from the determined position of the flow vector and the input, the one parallel to the flow vector and the one perpendicular to it Component of the stator current defining setpoints, the control variables for the control of the converter valves.

If one describes the prevailing in the asynchronous machine magnetic field by a flux vector lying in the direction of the field axis and sets that in the stator windings flowing currents merge into a current vector, it is advantageous for converter-fed asynchronous machines, to control the stator currents in such a way that with the component of the stator current parallel to the flux vector (magnetizing current) the river ζ. B. on a, constant Amount held and with the component perpendicular to the flux vector (active current) a desired value of the torque or the speed can be set. Such a field-oriented operation is from the German Patent 19 41 312 known. Setpoints are thereby given that the stator current vector in a rotating with the flux vector ("field-oriented") coordinate system Specify in amount and angle or in the Cartesian components. In order to derive the corresponding control parameters for the stator current to be supplied by the converter

KbI 2 Shi / 08/05/1980

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If necessary, the field-oriented specified stator current setpoint vector must be transformed into the stationary reference system of the stator windings, including information about the position of the flux vector is required. 5

The information can be obtained through a flow computer from the corresponding Values of stator current and stator voltage can be obtained. According to DE-PS 18 06 769 this can be achieved happen that from the star voltage of a machine terminal the ohmic voltage drop at the relevant Stator winding, which is given by the product of the current through the stator winding and the ohmic resistance, as well as the inductive voltage drop, which is given by the product of the relevant leakage inductance and the time derivative of the conductor current is subtracted. This will cause the occurring on the winding EMF is formed from which the flux induced in the direction of the relevant winding axis is calculated by integration will. As with the stator current, the stator voltages, ohmic voltage drops, Stray voltages, the EMF and the flux to vectorial quantities, each from the to the individual stator windings belonging individual quantities can be combined to form a common vector. With a three-phase As a result, induction machines can have two components by detecting the EMF or the flux in two stator windings of the EMF vector or the flux vector in one of two winding axes enclosing an angle of 120 ° Spanned coordinate system can be determined, it being possible by a coordinate converter from this oblique coordinate system into a corresponding, stationary Cartesian coordinate system pass over, which is referred to in the following with the indices Οί, β is in contrast to those marked with Ip and ψ2 field-oriented coordinates. The conversion can be done at the output of the flow computer, it can

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but already when the stator current and stator voltage are recorded take place so that the flux calculator of the stator current vector and the stator voltage vector in the oblique angle or can be specified in the Cartesian coordinate system. It is also possible to use the EMF vector Integration leading to the flux vector after subtracting the ohmic voltage drop from the stator voltage vector and to take into account the inductive stray voltage after integration, the product deducted from leakage inductance and stator current. Such a flow calculator is z. B. from the German Patent 28 33 542 known.

This flux calculator, which is essentially based on the stator voltage vector and forms the flux vector by integrating the EMF, can be referred to as a "voltage model" will. This model often meets the requirements for accuracy even without precise knowledge of the stator resistance and control dynamics when operating an asynchronous machine, provided that the stator frequency of the asynchronous machine exceeds about 10 1 of the nominal frequency. The voltage drop at the stator resistance is then namely negligible compared to the EMF, so that an inaccurate detection and Setting the ohmic voltage drop in the flux detection is less of a problem. For lower frequencies, however is an exact determination of the flux from the exact knowledge of the temperature-dependent stator resistance R addicted. Furthermore, the open integration method used in the stress model requires a Zero point drift a complex adaptive DC component control, which leads to a corruption at low frequencies leads to the flow detection and also affects the control dynamics in the upper frequency range.

The object of the invention is the device of the opening

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specified type by using another flow calculator so that even at low frequencies a better flow detection and a higher dynamic accuracy is achieved in the entire frequency range. 5

This is achieved by providing the flux calculator with the position of the rotor axis in addition to the values for the stator voltage vector is entered and in the flow computer, taking into account parameter values, the rotor resistance and correspond to the stator resistance of the machine, the totality of the given position of the rotor axis PARK's equations describing electrical quantities of the asynchronous machine are solved. The location of yourself too a solution of the PARK equations belonging to the flow vector is in the form of corresponding signals on the flow computer tapped.

While in the known flow computer only the EMF vector of the machine is determined and from this the flow is determined by integration is calculated, so according to the invention in the flux calculator, starting from the stator voltage vector and the Rotor axis rotation angle, the differential equations for Stator current vector, stator voltage vector, EMF vector and flux vector solved. As a further machine parameter parameter values are used in the flow calculator for the main inductance and the leakage inductance, but the are only slightly variable and are set independently of this invention. Instead of the known Flux computer required stator current vector is information about the position or the movement of the rotor axis is used so that it is not necessary to use the mechanical part of PARK's equations, i.e. H. Equations, the torque delivered by the electrical variables with the mechanical torque of the Maschi-5 ne and the rotor rotation link, to solve. Through this

-i ·

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will also be a good match between Model and machine achieved in terms of dynamics.

Since in the solution of the differential equations especially the Parameter values for the stator resistance and the rotor resistance are entered, the accuracy of the model thereof is depends on the extent to which the parameters used in the model for rotor resistance and stator resistance match the corresponding Match the machine parameters. It is therefore advantageous if the flow calculator for the parameter value the stator resistance and / or the rotor resistance Input inputs for entering adjustable parameter values contains.

To enter a rotor resistance parameter value that corresponds well to the rotor resistance, it is in accordance with an embodiment of the invention advantageous to tap a size on the flow computer that corresponds to the solution of the equations in the flux calculator determined stator current vector. Since the stator current vector is is a vector that revolves perpendicular to the axis of rotation, which by magnitude and angle or by its components is determined in a given coordinate system, can advantageously be used as the determining variable of this vector 5 component perpendicular or parallel to the entered stator voltage vector or in particular the amount of the Stator current vector can be used. From the stator currents tapped at the asynchronous machine, a corresponding The size determining the stator current vector of the machines is formed. At the input input for the rotor resistance parameter value an integral controller is provided to which the difference between the two determining variables is fed.

In this embodiment, it is assumed that the

Ü3G34252

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Machine and the flux calculator the same stator voltage vector is given. Consequently, the same also apply Pie charts, with only the slip scales differing if the machine and model differ Run out. Since, however, the actual rotational movement of the rotor is entered into the flow computer is, the flux calculator determines a model stator current vector different from the actual stator current vector. The parameter value for the rotor resistance is now adjusted by the integral controller as long as until the model stator current vector tracks the actual stator current vector. After the comparison has been carried out of the stator current vectors, there is then a good match between the actual rotor resistance and the corresponding parameter value.

According to another embodiment of the invention, the parameter value for the rotor resistance is set the EMF vector of the machine is tracked to a corresponding EMF model vector. To form the EMF vector The machine uses an EMF detector as it is used as a flow computer in the prior art mentioned at the beginning is known. This EMF detector determines the EMF of the machine from the stator current and stator voltage Size. The EMF is also a plane vector, so that the absolute value is the determining variable or particularly advantageously those that are parallel to the entered stator current vector or, in particular, those that are parallel to it vertical component (dummy component) can be used. Furthermore, one is the origin of the magnetic The flow in the machine leading processes simulating arithmetic model circuit is provided, which is based on the Stator currents, the rotor position of the machine and one adjustable parameter value for the rotor resistance a model flow vector is calculated. In one calculation stage

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the difference between the variable determining the machine EMF and one derived from the model flux vector, the corresponding EMF of the model is formed. The difference between these variables is used by a rotor parameter controller whose output is on the one hand the input input for the rotor resistance parameter value the arithmetic model circuit and on the other hand the input input for the rotor resistance parameter value of the flow computer is fed.

This embodiment assumes that the arithmetic logic element and the machine is given the same stator current vector so that they are congruent here too Pie diagrams apply that differ only in the slip scaling, which is dependent on the rotor resistance are. Since the rotor angle of rotation of the machine is also impressed on the arithmetic model, the arithmetic model circuit determines therefore a model EMF vector for the given slip, which deviates from the EMF vector of the machine, if the rotor resistance in the arithmetic model circuit differs from the rotor resistance of the machine Parameter value is entered. The rotor resistance parameter value of the calculation model is now as long as changed until the EMF model vector tracks the machine EMK-5 vector. After the adjustment is correct the parameter value used in the calculation model corresponds well with the rotor resistance of the machine. Therefore, the The value pending at the rotor resistance parameter controller is then also sent to the flux computer as rotor resistance parameter value can be entered.

An EMF model vector is advantageously formed in the computing stage by differentiation of the model flux vector. The EMF vector formed by the detector and the EMF model vector is fed to a device which has at least one vector analyzer for generating the absolute value and

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contains a subtracter to form the difference between the magnitudes of the vectors. But the facility can in addition to the subtraction element also contain at least one vector rotator instead of a vector analyzer. The vector rotator is supplied with a signal generated from the stator current vector on a vector analyzer, which signal contains the Describes the position of the stator current vector in the fixed reference system. The vector rotator then performs a coordinate transformation the entered vector quantities from the stator reference system (indices Ä, ß) into one with the stator current vector revolving reference system (indices j 1, j 2). Therefore the device supplies two coordinates, the vectorial one Difference between the machine EMF vector and the EMF model vector in the reference system rotating with the stator current correspond. One of the coordinates in this rotating reference system is then used to adjust the EMF vectors used. The component perpendicular to the stator current (reactive component) is advantageously used. the The reactive component of the machine EMF vector is always equal to the reactive component of a sum vector from the EMF vector and ohmic voltage drop, since the ohmic voltage drop is always only a drop in the active voltage and thus represents a vector lying parallel to the stator current. This sum vector can be in a simple manner are formed by the fact that in the EMF detector only the inductive leakage voltage drop from the stator current vector, d. H. the product of the leakage inductance and the time derivative of the stator current is subtracted. the The reactive component of this sum vector is used as the variable that determines the EMF vector, together with the EMF model vector determining reactive component of the EMF model vector supplied.

The fact that the component (active component) of the sum vector which is parallel to the stator current vector can be used here of the active component of the machine EMF vector

C or after the active component of the EMF model vector has been matched) only about the ohmic voltage drop, i.e. the product of the stator resistance and the amount of the stator current vector, differs. Therefore, the vector analyzer that determines the angular position of the stator current vector is used the amount of the stator current vector is also formed and applied to the divider input of a divider element. At the same time, the vector rotator, which is the coordinate transformation of the difference between the machine EMF vector and EMF model vector, the effective component of this vectorial difference is also calculated. This active component of the vector difference is fed to the dividend input of the dividing element, so that its output at the same time a calibrated parameter value when the EMF reactive components have been calibrated for the stator resistance.

In addition to the flux calculator, this embodiment requires an EMF detector and a computational model circuit and is therefore relatively expensive, but it is characterized by high accuracy and good dynamics. For lower requirements, it can also be advantageous to determine the stator resistance at the flux calculator input for the corresponding parameter value Provide arithmetic element, which is acted upon by the stator temperature and by correcting a temperature-independent set output value with a temperature correction function stored in the arithmetic unit forms a temperature-dependent rotor resistance parameter value. Taking into account the temperature of the Stator winding can be done in a simple manner that the temperature-independent output value with the stator winding temperature is multiplied.

The invention is explained in more detail with the aid of several exemplary embodiments and figures.

80 P31 6 7DE

According to FIG. 1, an asynchronous machine 1 is fed from a three-phase network N via a converter which consists of a network-commutated rectifier 2, an intermediate circuit 3 with an impressed intermediate circuit current, and a self-commutated inverter 4. For the ignition of the converter valves, a converter control 5 is provided, to which a stator current setpoint vector i_ * is specified in that the component i ^ M C magnetization current parallel to the field axis and the perpendicular component ί * - _Λ are entered separately. A vector analyzer 6 uses this to determine the amount i * of the setpoint vector, which is compared with the actual value of the stator current amount i and is input to a current controller 7 in order to supply a control variable for the ignition controller 8 of the rectifier 2 from the control deviation. The vector analyzer 6 also provides the projections of a unit vector onto the two field-oriented coordinate axes, the unit vector as a control vector describing the position of the stator current setpoint vector i * in the field-oriented coordinate system, which is rotated by the flow angle f compared to a stationary Cartesian reference system (stator reference system). The projections sinot, cosoi of this unit vector are transformed into the stator reference system by means of a vector rotator 9, to which projections sin if, cos ij> of a unit vector pointing in the direction of the field axis are entered. This angle information about the position of the field axis is picked up on a vector analyzer 10, to which the components%, S ^ of the flux vector Ψ in the stator reference system are entered. Such vector analyzers and vector rotators are z. B. described in German patent application 29 19 786.2. At the output of the vector rotator 9, the components of the control vector are now available in the Cartesian stand reference system, from which in a coordinate rotator 9 ¹ the components relate to three, offset from one another by 120 °

80 P3 16 7DE

Strong winding axes of parallel axes are formed. The coordinate converter 9 ′ thus supplies the control voltages for the ignition control device 9 ′ ^{1 of} the self-commutated inverter 4.
5

Since the field-parallel component i * ^ determines the amount of the flux via the magnetizing current, the setpoint ί * φ. for the magnetizing current are formed by a flux regulator 11, to which the control deviation between the desired flux value ψ * and the amount of the flux vector Ψ formed at the vector analyzer 10 is fed. The torque or the speed of the asynchronous machine can be controlled via the setpoint ϊ * φ ₂ ^ ^{he field-perpendicular stator current component (active current).} B. a speed controller 12 is provided, which from the control deviation between a predetermined target speed ω * and a corresponding actual value, the time derivative A. of the rotor position tapped via a rotor position sensor 13 (rotor position "K) forms the active current required to set the target speed.

According to the invention, the angle information (sin iP and cos vp) is supplied by a flow computer 20 via the flux vector. The angle λ of the rotor axis picked up by the rotor position sensor 13 and the stator voltage vector U are entered in the flow computer 20. Of the stator voltage vector U is the embodiment according to Figure 1 in the form of its two components _υ Λ, U λ in the Cartesian stator reference system defined, which are tapped by means of a coordinate converter 21 from corresponding voltage transformers to two machines leads R, S. In principle, the stator voltage vector U can also be specified in a different coordinate system, e.g. B. a rotor-related coordinate system is possible, since the corresponding arithmetic modules are available for coordinate conversion

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stand. In the given case, the setpoint values can also be used instead of the actual values with a correspondingly good regulation and operation of the asynchronous machine with impressed voltage.
5

The system of equations to be solved in the flow calculator is:

In the PARK equation system to be solved in the flux calculator, the stator current i_ and the rotor current i become a magnetizing current i

educated. Corresponding to the main inductance L, stator leakage inductance L ^s , which in the context of this invention is also simply referred to as leakage inductance U, and the rotor leakage inductance, the magnetizing current leads to the build-up of a flux ψ in the stator and a flux ψ in the rotor:

= L i ₊ L * ⁵ i ^S (2)

(J

= L ί _{μ +} L - i (3)

These vector equations are valid in every coordinate system because of the invariance of the vector addition. The conversion of the current coordinates given in the stator-related system (indices O <, ß) into a coordinate system (coordinates d, q) revolving with the rotor (rotor position angle λ) is given by a corresponding rotation matrix D (^ ₁ ):

P316 7DE

⁼ 1 ^(λ) "id, q C4-)

^{However, the time derivatives of the fluxes * f s} and Ψ in the form of the induced emf are included in the equations for the voltages on the stator and rotor windings. These equations are no longer invariant to coordinate transformations. Rather, the following applies to the stator voltage vector u in the stator-related coordinate system:

^ «, ^{Ss =} itf, ß · ^{rS +} It -of, ß. C5D

The voltage equation for the squirrel cage rotor of the asynchronous machine is to be written in the same way in the rotor reference system and it applies
,

^U "id, q ' ^{R +} dt -d, q (6)

The air gap flow CH main flow) Ψ can be introduced by H [= L 'i. , CD

so that from (5) or (6) and (2) follows:

~ ^a ' ^{ß ld) ß + dt} i Oi, ß ⁺ dt - «, ß, CHD

where applies

These equations go e.g. B. ims the dissertation of

F. Blaschke:
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"The method of field orientation for controlling the induction machine", TU Braunschweig 1974, pages 6-9, if one takes into account that the asynchronous machine instead of an excitation winding and a damper winding, there is only one short-circuit winding in the rotor.

Corresponding equations are z. B. also in "Siemens-Forsch, -u. Entw.-Ber. ", No. 1/1972, page 184, equations 2-6. The equations given there

1Ü 1 and 7, which describe the electrical torque of the machine and _w the calculation of the angular speed of the rotor by linking the electrical and mechanical torque, are not required because the flow calculator 'has entered the necessary information about the rotor's angular speed via the rotor position λ . Corresponding equations can also be found in the equations given in "Siemens-Forsch, -u. Entw.-Ber.", No. 1/1972, pages 157 - 166 for the more general case (synchronous machine) in the rotor reference system. There is also given a circuit for solving these differential equations, which can be transferred to the needs of the flow computer 20 used here. In this circuit, a mechanical part is provided in order to calculate the rotor position by combining the electrical torque. In the flow calculator according to the invention, such a mechanical part is not required, but is replaced by the direct input of the rotor position angle.

In Figure 2, the internal structure of the flow computer 20 is shown schematically.

In this circuit, the vector ψ in the rotor-related coordinates tf · ,, ψ is calculated in a flow arithmetic unit 30 according to (I ¹ ) and (III) and then

49.

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Conversely entered angle functions sin X., cosX of the rotor position angle λ converted into column-related coordinates Ψ ^ , Vq (transformation circuit 31). In differentiating circuits (32,32 ') the stator-related component ε _Λ , e ^ of the EMF vector £ = -j £ SP is calculated and the stator-related component of the stator current vector ά in a current calculator (33, 33'). determined. For input into the flux calculator, these stand-related components i _Ä , ϊλ are transformed again in a transformation circuit f34 into the rotor reference system in which the flux calculator works.

To understand the circuit of the flux calculating element 30 given in FIG. 2, (III) and (I ') are combined to

u U at I η TiJ. ί ^ "" J .. ■

In the upper part of Figure 8 is a corresponding circuit shown schematically in which the first easy Products of the right side from i, by means of a dif-

reference element 80 and corresponding proportional elements R ^L , L and the third product of the inverted output variable ¥ ■, by means of a proportionality

1 L adhered duct 81 (factors ^ -, R) formed are. These three products and a fourth product are fed to a sum point 82, so that the equation is completely present at the sum output if the fourth product after multiplication by ^ - and inversion from the sum signal - ^ r- is formed. The sum signal by integration (integrator 83) results in the sought-after flux component H \

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The lower part of Figure 8 shows a simplification of the service Circuit, now instead of the differentiating element 80, a timing element 80 'with the time behavior

, (TI.

(1 + S «-p) is used (S = operator of the Laplace transform). This circuit can be described by the following relationships, which are determined by Laplace transform will be obtained:

ι 6 ^l mi I ^

sc, ₊ i = _L,. - * d ₊ i _a / ei * s--

^L.

V! ₊ f _L ci + £ »-i _d ci + sig),

S *

1 / l + s. (1 + l? ^L / _l D / R ¹ :

These relationships lead to the circuit indicated in FIG. 2 if R _{1 is set} proportional to L, R ₂ is set to be proportional to L and C. is ^{set to be proportional to 1 / R L.} The same applies to the component Ψ.

To calculate the current components i ^, in are used in each case Smoothing members 33, 33 '. Because equation (II) can be transformed to

_T ff. D. αφ _D S.

dt Ot * dt ^Λ

To display '. A circuit according to FIG. 9 can be used, the component tapped at the differentiating element 32 - e ^ = ~ dt ^ '^ ^{e E} i ⁿ g ^an g ^{s size} u (^ as well as the output variables i «tapped at the output 91 of an integrator 92 - after amplification (factor RD and inversion - are fed to a sum point 93, the sum signal being fed to the integrator input.

BATH ORIGINAL

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ne circuit. The stator leakage inductance L 'is represented by the capacitor C ₂ and the reciprocal stator resistance by the resistance R-. This structure of the flow computer for solving the differential equations of the asynchronous machine is known per se from the stated prior art. For the invention are the

1 -j capacitors C ₁ and C ~ proportional to ^ L and pS change-

Little to keep them in line with the true machine parameters

τ S
Adjust R and R. Furthermore, the value * of the current components I ₀ ,, iß and / or the flow components ^, ^ ß calculated in the flow computer can be brought out at outputs 34, 34 'and 35, 35'. The current components represent values i _M,. ί _ΜΛ represent that of the parameter setting

TQ M J- * lYL ρ *

Rj., .R "of the flow computer correspond. Using the vector analyzer 10 (FIG. 1), the angle signals sin φ ₅ , cos (f _s , which correspond to the angle <ρ _ς between the flow axis and the oC axis of the stator reference system, can then be formed from the flux components H ^ w ^, Ψ _{Μ «} when the parameters

SL
ter values R .. and R _{M of} the flow computer are set with sufficient accuracy to the machine parameters R and R. It should be noted, however, that the flow calculator

further parameters, e.g. B. L, L and L, used for * ^ an exact determination of the position of the flow vector as well

must be set with sufficient accuracy. 25th

The flow vector Ψ calculated in the flow computer 20 describes the flow of the machine the more exact, the more precisely the parameters

ς L

meter values R ^ for the stator resistance and Rj. for the Rotor resistance match the corresponding resistance values of the asynchronous machine. That's why provided on the flow computer 20 input inputs to the Parameter values to the corresponding machine values to adjust.

In many cases it is necessary to adjust the temperature

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temperature dependence of the stator resistance R of the machine to consider. In the embodiment of Figure 1 happens this in that a temperature-dependent value

which is obtained by the fact that an output

input value R ", which is set to the stator resistance at a certain reference temperature, is multiplied ^{by a correction function for the stator winding temperature v * 3.} In some cases it is sufficient to enter the receipt

G
upstream for R _M a multiplier 23 in which the

S öS

Output value R _{Q is} multiplied by the stator temperature tj · wi rd.

An identification circuit is connected upstream of the corresponding input of the flow computer 20 to input a rotor resistance parameter value Rw that is matched to the rotor resistance R of the machine. This identification circuit is based on the fact that the machine and the
Flux calculator the same vector is given for the stator voltage. Consequently, congruent pie diagrams apply to the flow computer and the machine, with only the

L.
M.

Slip scale for R ^ RrJ is different.

The circle diagram is recorded in FIG. 3, the scale attached to the outside of the circle for the

Machine, the scale on the inside for the model in the case R „> R ^J applies. The stator current i_ of the machine shown in FIG. B. the slip 0.05. By entering the rotor position, the flux calculator 20 has entered the same slip 0.05, so that the calculated stator current i n results in the flux calculator. The entered rotor resistance parameter Rw is now changed in the identification circuit until ji = _L, and thus R ^L = R ^ also applies.

To implement this principle, an integral controller 24 is provided at the input input for R "of the flow computer,

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the respective cine determining variable of the hourly current vector i. and model stator current vector L. * which is calculated in the flux calculator when solving the corresponding differential equations are supplied. In particular, the amounts i and i ^ of the stator current and the model stator current determined in the flux calculator can be used as the determining variable. The following always applies to RR ^> 0 i - if- ^ O · The monotony between i - L, and R - R ~ is only disturbed at very low frequencies and very small slips, so that a reversal of sign may be taken into account in these extreme operating states must become.

The formation of the amount Lj of the stator current vector L · calculated in the flux calculator. can be done by means of a vector analyzer 25, the coordinates determined in the stator reference system ijytß In ₀ ^> the calculated flow computer 20 ^{in the} stator current vector are supplied in a simple manner. The amount i of the stator current i is analogously. of the machine is determined by means of a vector analyzer 26 to which the Cartesian coordinates I ₀₆ , in, of the machine current are supplied. These Cartesian components are formed in that the machine _{currents i R} , ϊ _{ς are} tapped in two machine lines R, S by means of current transformers 27 and transformed in a coordinate converter 28 into the Cartesian stator reference system.

In FIG. 4, the nature of the circuit according to FIG. 1 is repeated in a simplified representation. The system converter / machine is denoted by 40, the stator voltage vector being indicated by the double arrow U <*. , n, to indicate that it is the two components of a vector in the stator frame of reference. This stator voltage vector is also input to the flux calculator 41, which also receives the information from the machine about the stator winding temperature 17 * Cd. H. the temperature-

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Correction for the set stator resistance parameter

S λ

ter values R ,,) and the rotor position Λ. receives. The flow computer 41 supplies the information about the position and size of the flow vector, also symbolized by a double arrow Ψ, which is required by the converter control. The running resistance identification circuit consists essentially of the described vector analyzers 25 and 26 and the integral controller 24, the two stator current _{vectors again being indicated by double arrows i t)} «and jL. ^ «Are indicated.

The exemplary embodiments according to FIGS. 5 and 6 relate to a different circuit for identifying the rotor resistance and / or stator resistance of the asynchronous machine based on the use of a "current model" designated arithmetic / model circuit 50 is based. This Current model to identify the rotor resistance and, if applicable, the stator resistance is included in the German patent application filed at the same time

entitled "Method and apparatus for determining the Rotor resistance of an asynchronous machine "of the same Applicant described, the content of which is to be attributed to this application, but described here only in broad outline shall be.

The arithmetic model circuit 50 is based on the stator current vector i_ impressed on the asynchronous machine and uses the rotor position angle % tapped on the asynchronous machine as further information. A rotor resistance parameter value Rw is also entered into the current model and a model vector for the flux vector of the machine is calculated by means of this parameter value in a model circuit which simulates the dynamic processes in the asynchronous machine. Since in this case the electricity

: ·> Γ) model 50 and the asynchronous machine have the same stator current vector is embossed, dec-

4252- ^: -. ^

VPA 80 P 3 1 6 7 DE.

Similar circular diagrams with different slip scaling for the case R "φ R. However, since the actual rotor position and thus the actual slip is given to the current model at all times, the model flow vector Ψ, differs. from the actual flow vector Ψ. Likewise, the model emf vector e i, which is produced by differentiation from the model flow vector, also differs from the emf vector e of the machine. Hence the

—M -

A rotor resistance parameter controller 51 is connected upstream of the input of the current model for the rotor resistance parameter value, to which the deviation between a variable determining the EMF vector £ of the machine and a corresponding variable determining the model EMF vector £ _M is fed. The rotor resistance parameter value R ,, is now changed by means of the controller 51 until the two EMF vectors <e, e *, coincide, ie the difference between the determining variables disappears at the controller input. A value is then available at the controller output which corresponds to the rotor resistance R with sufficient accuracy.

In principle, 51 can be used for the adjustment on the controller of the EMF vectors the corresponding flux vectors are used. For this purpose, an EMF detector can be used the stator voltage vector U by subtracting the ohmic voltage drop and the inductive stray voltage and integration the flux vector 4 ^ of the machine can be formed. In a subsequent arithmetic circuit, the Difference between two the respective vectors Ψ, ti. determining Formed sizes and fed to the controller 51. The amounts of the vectors serve as determining quantities, see above are the components of the vectors each to a vector analyzer and those pending at the vector analyzers Values of the vector amounts fed to a subtraction stage.

In terms of circuitry, it is easier to adjust the

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Rotor resistance not from the flux vectors, but
start from the EMF vectors. The computing circuit
then contains a differentiating stage in order to obtain the model emf vector e i by component-wise differentiating the model flux vector Hi. When switching to
However, FIG. 5 is not based on the magnitudes of the EMF vectors, but on their components perpendicular to the stator current vector _i (reactive components, index j 2). Since the ohmic voltage drop is a pure real voltage drop and therefore represents a vector pointing in the direction of the stator current vector, the ohmic voltage drop does not contribute to the reactive component of the EMF vector. This results in the EMF detector
a simplification which at the same time also allows the stator resistance of the machine to be identified.

According to FIG. 5, the vector of the inductive stray voltage is subtracted component by component from the stator voltage vector U in the EMF detector 5 2 (subtraction point 53). The inductive leakage voltage vector results from component-wise differentiation (differentiating stage 54) of the
Stator current vector and multiplication by one the
Descriptive leakage inductance of the stator windings
Parameter L. Since the subtraction of the ohmic voltage drop required for the EMF calculation is dispensed with in the EMF detector 52, the EMF detector delivers the corresponding components S ₀ ^, s ^ of the sum vector _s instead of the Cartesian, stator-related components of the EMF vector the EMF vector and

the vector of the ohmic voltage drop (Figure 6). There
the Cartesian components of a difference vector from two vectors are equal to the differences of the corresponding components of the vectors, the controller 51
Difference to be entered between the reactive components of £ and

c? _M formed by initially sub-

VPA 80 P 3 16 7DE

traction (subtraction point 55) is the difference vector
s - e _{A / I is} formed. After subsequent reinforcement
the Cartesian components of this difference vector are applied to a vector rotator 56, which this
Vector transformed into a coordinate system revolving with the stator current vector. For this purpose, the quantities sin ^, cos ^ are fed to the vector rotator, where y is the
Represents the direction of the stator current vector in the Cartesian stator reference system. This information about the direction of the stator current vector is formed by a vector analyzer 57 to which the Cartesian components i ^, ip> of the stator current vector of the machine are fed. The vector analyzer 57 also calculates the amount i des
Stator current vector that corresponds to the divisor input of a divider

dier member 58 is supplied.

_{The components of the difference vector (s - £ M} ) denoted by the indices j1 and j 2 are thus present at the output of the vector rotator 56. The reactive component (js - e_ ^) j 2 of the difference vector is in accordance with the foregoing, equal to the difference e ~ -. E ... ₂ of the reactive components of the machine EMK-vector "5 and the model EMK-vector e".
This difference is fed to the input of the controller 51 and adjusts the parameter value Rw in

of the arithmetic model circuit 50. When the machine and model have been compared, the reactive component e is correct. _? of
Machine EMF vector ei corresponds to the corresponding reactive component e _{Mm2 of} the model EMF vector, but the active component of the difference vector s - e _M is equal to the ohmic voltage drop R. i on the stator windings of the machine. Therefore becomes the active component

Cs -. £ ") j 1 ^ ^em dividend input of the divider switched 58 so its output is at a sufficiently coincident with the StHnderwiderstand R of the engine value This value can now to the flow computer * 41st

303-252. ^: . .

VPA 80 P 3 1 6 7 OE

can be entered as the stator resistance parameter value R ". To enter the corresponding rotor resistance parameter value R "in the flow computer 41 can, for. B. also the Identifitzierungs-S already explained with reference to FIG circuit with the vector analyzers 25 and 26 and the integral controller 24 can be used. But it can on the other hand also the one at the output of the rotor resistance parameter controller 51 pending value for the identified rotor resistance R of the machine to the flow computer 41 are supplied. The elements 24, 25, 26 are then omitted and that shown in FIG. 7 results Circuit.

Compared to the known device, in which the information necessary for the converter control about the machine flux vector is formed by means of a voltage model, it allows the device according to the invention, to apply the current model, which is superior to the voltage model at lower speeds, but with an incorrect

SL adjustment of the resistance parameters R _M , R _M and an associated miscalculation of the flow vector can be avoided by using the flow calculator according to the invention.

VPA 80 P 3 16 7DE

Together f assung

The invention relates to a flux calculator (40) which _{calculates the flux vector (components T 5 ^ HV) from the stator voltage vector (components U 01} , U ^) and the rotor position angle by using the electrical equations of the

SL asynchronous machine solves. The parameter values Rw, Rw for The stator resistance and rotor resistance are preferably tapped on controllers. The stator current amount i and the one belonging to the calculated flow, from the running resistance parameter dependent model current amount iw> are as a rule

«, Since η dead · ^ΐ 7ΐΐπηιΡίΐΤ" ϊΎ * + "ι

deviations are fed to the Rri controller and compared to one another if R "is set exactly. It can also be calculated in a calculation model (50) from stator current vector (i ^ rt), run creation angle (TO and R _M a model flow vector C ^ w ₀ J.) on the one hand and in an EMF image (52) the actual EMF vector . _{The model vector (£ Moi} n,) assigned to the flux or the EMF and the actual vector (js _Λ η ) are the same if Rw is adjusted to the actual rotor resistance. If the ohmic voltage drop is not taken into account when forming the actual EMF vector (see oi, / 0, the stator resistance can be determined from the difference between the two vectors Component of the current setpoint specified.

FIG. 5

SO-

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Claims (10)

Claims - τ / - VPA 80 P 3 16 7 QE (1.) Device for operating a converter-fed asynchronous machine (1) with a flux computer (20) which determines the position of the flux vector (components ^ »%) from the values entered for the stator voltage vector (components U ^, U ^), and a converter control (5), the setpoint values that determine from the determined position (sin φ _s , cos cp _s ) of the flux vector and the input values that are parallel to the flux vector and the components perpendicular to it (i * \ ^> ⁱ * W2 ^ of ^the stator current vector, the control variables for forms the control of the converter valves, characterized in that the flow computer (20), in addition to the values (U ₀ ^, U ^) for the stator voltage vector, the position (angle "λ) of the rotor axis is entered and in the flow computer taking into account the rotor resistance (R) and parameters corresponding to the stator resistance (R) of the machine «Τ values (R ^, R ^) the totality of the given position the rotor axis the electrical parameters of the asynchronous machine descriptive PARK's equations are solved, and that the position of the belonging to a solution Flux vector corresponding signals (sin Φ. Cos fj am Flow computers are tapped (Fig. 1). 2. Apparatus according to claim 1, characterized in that the flow computer (20) has an input input for entering a variable parameter value (R ^ f) for the rotor resistance (Fig. 1). 3. Apparatus according to claim 2, characterized in that the flow computer (20) a determined in the flow computer, belonging to a solution stator current _{vector (model stator current, components i M} ^, ijyj η) determining variable (vector amount ijj is tapped that from the stator currents (i _R , ig) one 2, VPA 80 P 3 16 7 OE corresponding, the stator current _{vector (components ϊ Λ} , in) of the machine determining size (vector amount i) is formed, and that an integral controller (24) is provided at the input input for the rotor resistance parameter value (R ^), to which the difference (i ^ - i) of the two determining variables is supplied (Fig. 1). 4. Apparatus according to claim 2, characterized in that an EMF detector (52) consisting of stator current (i ^, ») and stator voltage (U ₀ Of ?.) a variable (S.) that determines the EMF of the machine (40) is determined by a computational model circuit (50) which, based on the stator current (i. _Λ> «), the rotor position (X) of the machine and an adjustable parameter value (RfJ) for the rotor resistance, which simulates the processes leading to the creation of the magnetic flux and _{calculates a model flux vector (Ψ Μ} ".,"), A computing stage (60) that calculates the difference between the the machine EMF determining variable (S. ") and a variable derived from the model flow and determining the EMF of the model (^ yIy ₂ ) is calculated, and a rotor resistance parameter controller (51) is provided to which the difference ((i3 -, S] Vj) ^ p) and the output of which is fed to the input inputs for the rotor resistance parameter value of the arithmetic model circuit (50) and the flow computer (51) (FIGS. 5 and 7). 5. Apparatus according to claim 4, characterized in that in the computing circuit (60) the EMF vector (£ -x »ft) formed by the EMF detector (52) ^{un <} * ^e ^ - ⁿ by differentiation from the model flow vector (if _M et, £) formed EMF model _{vector (e_ M} χ, η) is fed to a device which, by means of at least one vector analyzer and a subtraction element, forms the difference in the amounts (e, e _M ) of these vectors, which serves as the difference between the determining variables . - τ / -3 VPA 80 P 3 16 7DE 6. Apparatus according to claim 4, characterized in that in the computing circuit (60) of the EMF detector (52) formed by the EMF vector (£ α .tß. ) ^{And a} by differentiation from the model _{flow vector (Ψ * Μ} ^, ^ ) formed EMF model vector (% _Ä , ^) a device (55, 56, 57) which contains at least one vector rotator (56) and a subtraction element (55) for forming the component ((_s - e ^) ^) of the difference (s, - e _M ) of the vectors (Fig. 5). 7. Apparatus according to claim 6, characterized in that the EMF detector from the stator current vector (U ^, «) by subtracting the inductive stray voltage (L · jifc i <*» (i) ^the sum vector (j3 _α , η) from EMF and ohmic withstand voltage drop is determined and this sum vector is supplied to the computing circuit (60) as the EMF vector of the machine (FIG. 5). 8. Device according to one of claims 1 to 7, characterized in that the Flux calculator (20) has an input input for entering an adjustable parameter value (Rj,) for the stator resistance (R) of the machine (Fig. 1). 9. Apparatus according to claim 8, characterized in that at the input one of the stator temperature ($) acted upon arithmetic element (23) is provided, which by correcting a temperature-independent output value (R _Q ) with a temperature correction function ion (t>) a temperature-dependent stator resistance parameter value (R ^) forms (Fig. 1). 10. Apparatus according to claim 7 and claim 8, characterized in that the Arithmetic circuit (60) by means of the subtraction element (55) - yr-ψ. VPA 80 P 3 16 7 DE and the vector rotator (56) also the difference ((_s - the stator current-parallel components of the sum vector (, S ₀ (I (I,) and the EMF model _{vector (e_ M} φ ^ ), this difference is fed to the dividend input of a divider (58) whose divisor input is derived from the stator current (: L ^ , β ) is supplied to the amount of the stator current vector and its output is connected to the input input of the flux calculator (41) for the stator resistance parameter value (R ^) (Fig. and Fig. 7).